This chapter discusses the positive obligations under human rights law of states (contracting states) hiring private military and security companies (PMSCs) in situations of conflict. Based on analysis of the (quasi-)jurisprudence of the Human Rights Committee, the Inter-American Court of Human Rights and the European Court of Human Rights, it is demonstrated that, where violations have already occurred or have been alleged, the duty to investigate, prosecute, and punish obligates states to provide for a structure facilitating the reporting, follow up, and processing through the system of justice of such allegations. These provisions can, for the most part, be extended to the conduct of third persons and thus also to contractors providing coercive services, even where their conduct may not be attributable to the state under the law of state responsibility.